Synthesis of MgH2 using autocatalytic effect of MgH2

We describe the synthesis of MgH₂ using autocatalytic effect of MgH₂. The MgH₂ was synthesized by ball milling Mg with 5 wt% of MgH₂. The ball milling was carried out at different pressures of 15, 30 and 45 atm of H₂ followed by heat treatment (heating under vacuum and annealing at 30 atm of H₂ pressure (at 350 °C) for 10 h). It has been found that the MgH₂ synthesized using 30 atm of H₂ pressure during ball milling, followed by heat treatment and annealing (MgH₂30BM) is the optimum material as it has lowest desorption temperature (325 °C) faster rehydrogenation kinetic (6.60 wt% within 30 min at 300 °C and 20 atm hydrogen pressure). Also MgH₂30BM maintains the storage capacity of more than 6.00 wt% (loss of 0.6 wt%) after 10 cycles of de/re-hydrogenation. The as synthesized MgH₂ has superior de/re-hydrogenation properties and is ∼4 times cheaper as compared to MgH₂ procured from the chemical company like Alfa-Aesar. It is to be mentioned that under above mentioned temperature and pressure conditions the stand alone Mg (without having MgH₂ as catalyst) doesnot at all converts to MgH₂. The present study opens the gateway for economical synthesis of MgH₂ at large scale.